Apparatus and method for generating and storing energy in a portable energy storage device and using the stored energy to extend internal battery life

ABSTRACT

A portable energy storage device that can be brought to a desired operating condition (such as temperature) using an external power source to save the power in internal power cell and, when the external power source is disconnected from device to make it portable, the internal power cell of the device automatically provides output power to the load that is regulated by a pulse time modulation control circuit that senses the desired operating condition and provides power pulses to the load sufficient only to maintain the desired operating condition thus extending the life of the internal power cell in the portable device.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates in general to portable energy storage devices such as, for example only, heat generating elements. In particular, the invention relates to a hair curler, a hair straightener, a flat clothes iron, or any other such device for storing energy comprising a rotating flywheel, a light source, or the like. The energy storage device uses an external power source to bring the device to a desired operating condition thereby conserving internal battery power and to simultaneously charge internal batteries during the time that the device is placed in a base unit. When the device is removed from the base unit, the internally located batteries automatically provide energy to the heating element to make the device portable. A Pulse Time Modulation circuit regulates the battery power output at a level sufficient only to replace power losses in the device, again extending the life of the internal batteries.

2. Description of the Prior Art

In commonly assigned, copending patent application Ser. No. 11/094,000, entitled Portable Energy Consuming Device, and incorporated herein by reference in its entirety, there is disclosed an energy storage device such as a hair curler, a flat iron, a light source, or a rotating mass.

The device sits in a base unit when not in use. The base unit is connected to an external power source for applying power to the device to pre-energize the device to a predetermined level. For example, if the device is a curling iron, the external power, when the device is placed in the base unit, preheats the heating element to a predetermined temperature. The heating element of the device may be an AC heating element (in which case the external power source is a conventional wall socket providing AC power for preheating the device) or a DC heating element (in which case the external AC power source is rectified to a DC voltage that is used for preheating the device).

If an AC heating element is provided for preheating the device, a second DC heating element is located adjacent the AC heating element (which also preheats the DC heating element) and when the device is removed from the base unit, an internal DC power source is automatically connected to the DC heating element to maintain the existing preheat value.

Obviously the use of an external power source to pre-energize the device to a predetermined level (e.g. a predetermined temperature) extends the life of the internal batteries since the battery power is not expended in pre-energizing the device to the predetermined level. Such a system is disclosed in U.S. Pat. No. 6,664,516 which uses a PTC (positive temperature coefficient) thermistor that enables a high current to be provided to the heating element initially. However, as the time of application of the voltage increases, the electric current will decrease sharply until it reaches a low level whereupon it will remain relatively constant. Thus, power applied to the load is regulated by the PTC element serving as the load.

A device is disclosed in U.S. Pat. No. 4,857,702 that utilizes an external power source to recharge the internal batteries. This device requires the use of an AC wall socket plug that is pivotally mounted in the side of the device handle. When the plug is pivoted outwardly, it forms connections internally of the device to recharge the batteries. If the device is unplugged from the wall socket and the AC wall socket plug is pivoted inwardly of the body or handle, it provides internal connections that allow the charged batteries to heat the heating element. It will be seen that the battery cannot be charged while the heating element is being heated and the heating element cannot be heated while the battery is being charged.

As stated above, these devices prolong the life of the internal batteries by preheating the element with an external power source and, thus, saving the battery energy for simply supplying power to the heating element to maintain its heat.

As recognized in copending, commonly assigned, U.S. patent application Ser. No. 11/094,729, incorporated herein in its entirety by reference, an energy consuming device operates according to the well known equation P _(O) =P _(IN) −P _(L)   (1) where P_(O)=Power output, P_(IN)=Power input, and P_(L)=Power losses associated with the device.

However, if the device is an energy storage device, when the energy storage device reaches its operating condition (e.g. desired temperature, rotational speed, momentum, and the like), residual power, P_(R) becomes a factor in equation (1) above which becomes P _(o) =P _(in) −P _(L) +P _(R)   (2) where P_(R)=Residual Power and where “Residual Power” or “Residual Energy” is defined as “residual heat”, “rotational energy”, “mass momentum”, “linear motion”, “dynamic energy”, or any other term representing “potential energy” or “kinetic energy” in a device that is stored by the applied power. The residual power or a energy can be used to conserve energy used by such a device.

It can be seen in equation (2) that if P_(IN) is reduced to equal P_(L), then the residual power, P_(R), is sufficient to maintain the desired output power, P_(O). If the residual power, P_(R), is small, such as with a small electrical motor, because of low inertia and mass, only a small amount of energy can be conserved.

In particular, the invention relates to a method and apparatus for providing a portable energy storage and consuming device that has an external power source to cause the device to reach its desired operating condition (set forth above), an internal power supply for supplying power to the load of the portable device only when the external power source is disconnected, and a pulse time modulation device coupled between the internal battery or energy cell and the energy consuming and storing load to obtain a desired output power, P_(O), from the electrical load by simply supplying sufficient pulse time modulated energy, P_(IN), to the load to replace only load losses, P_(L), and to maintain only the residual power, P_(R), thus maintaining the desired power output, P_(O), and thereby conserving input energy, P_(IN), that would otherwise be wasted.

It is known to manually adjust input power to maintain a desired load. A circuit that is manually controlled to set a desired temperature is disclosed in commonly assigned U.S. Pat. No. 6,449,870 and U.S. Pat. No. 6,718,651.

Also, there are soldering devices that have a control circuit that shuts the power to the tip OFF when a certain temperature is reached and then turns the power ON again when the temperature falls below a desired temperature level. While it is done automatically, the power is not continuously regulated by a circuit that automatically varies the rate of pulsed (Pulse Time Modulation) power applied to the load to continuously maintain a desired operating condition such as temperature.

For a rotating energy storage device, such as a wheel, motor, and the like, when input power to the rotating device is removed, the motor or wheel continues to rotate by means of stored energy until frictional energy (power losses) completely expends the stored energy (residual power).

One circuit for manually providing input power, P_(IN), in an amount equal to the power losses, P_(L), is disclosed in commonly assigned U.S. patent application Ser. No. 11/055,235, incorporated herein by reference in its entirety.

It would be very desirable to have an improved device that provides continuous externally supplied electrical input power to an electrical energy storage device until the device reached its selected desired operating condition as long as the device is placed on a base unit during which time the internal batteries are charged and recharged. After the desired operating condition is reached (e.g. desired temperature), the device can be made portable by removing the device from its base by which action internally located batteries are automatically coupled to a heating element to continue to supply power to the device. An included novel circuit in the device then automatically reduces the input power from the batteries to the load (with the use of Pulse Time Modulation controlled by a feedback circuit) to an amount sufficient only to replace power losses to maintain just the residual power thus maintaining the desired power output with a minimum of power input thereby prolonging the battery life.

SUMMARY OF THE INVENTION

Thus, the present invention relates to an improved portable energy storage device (such as a hair curler and/or a hot air brush, flat iron, rotating mass, and the like) that utilizes an external power source to cause the device reach its desired operating condition (e.g. temperature, speed, momentum, and the like) and then utilizes internal batteries with a regulated pulse time modulated output as a power source providing sufficient power only to replace power losses, P_(L,) and to make the device portable.

As used herein, the term “external power source” means any one of AC, DC, RF energy, magnetically coupled energy, and the like. Hereafter, for simplicity, the term will be identified as simply AC or DC. The energy consuming device, when a temperature controlled device, may have either a single heating element for accepting an external DC power source output for preheating as well as the internal power source (at least one battery) output to maintain the desired operating level or an AC heating element for connection to an external AC power source to obtain the desired operating level and a separate DC heating element for connection to the internal power source to maintain the desired operating level.

With the present invention, an electrical energy storage device is brought to its desired operation condition by applying full input power, P_(IN), from an external power source as explained earlier until the desired operating condition is reached. Thus, the device is caused to store the desired potential energy without using the internal batteries (i.e. extending the battery life). At that point, the input power, P_(IN), is automatically reduced with the novel Pulse Time Modulation circuit disclosed in commonly assigned copending patent application Ser. No. 11/094,729, incorporated herein by reference in its entirety, to the amount of power losses, P_(L), occurring in the device and thus enables the residual power or energy, P_(R), that is stored in the device to substantially equal the desired output power, P_(O).

This is accomplished by providing a feedback circuit representing the desired operating condition of the energy storage device (i.e. temperature, rotational speed, light brightness, and the like) and generating a signal representative of the instantaneous value of the desired operating condition. That generated feedback signal is coupled as one input to a comparator. The other input is a variable time based electrical reference signal such as, for example only, a sawtooth reference waveform. When the feedback signal is less in amplitude than any portion of the sawtooth reference waveform, the output of the comparator is a pulse time modulated signal (PTM) that is coupled to, and actuates an electronic switch such as a power FET. The electrical load receives power from the power input source only when the electronic switch is actuated. The pulse time modulated signal is coupled to the gate of the electronic switch to automatically switch it ON and OFF at a rate sufficient to supply just enough power to the load to replace power losses (e.g. cooling in a heat storage device) and thus maintains the desired operating condition as determined by the feedback signal.

Also, for the improved circuit disclosed herein, where the input feedback signal is generated by a temperature sensor that provides a small input signal that must be amplified such as by a transistor, a fixed-bias may be provided to the base of the transistor rather than using self-biasing to form sharp, clean, pulses that are free from parasitic oscillation, 60 cycle hum, and the like.

The novel circuit, when controlling a portable light source, may use a feedback signal proportional to the heat of the light bulb filament or the light brightness as determined by any well-known light sensor, such as a cadmium-sulfide cell or a photo-detector, and thus provide power sufficient only to compensate for load losses such as filament cooling, and the like.

When controlling a portable rotating device that has momentum (stored energy or kinetic energy, the rotational speed of the device, as detected by an rpm indicator, for example only, can be used to generate a signal representative of the rotational speed and that signal can be used as the feed back signal, as described above, to drive the rotating device at a desired speed by supplying pulse time modulated signals to an electronic switch to apply power to the load sufficient only to compensate for load losses such as friction, system losses, and the like.

Thus, it is an object of the present invention to extend the life of batteries in a portable energy storage device by using an external power source to provide the power necessary to obtain a desired output power from an electrical load (such as to preheat an electrical load to a desired temperature), disconnecting the external power source and automatically connecting the batteries to the load and then using a Pulse Time Modulation circuit to regulate the battery power output to replace only the system and load losses thereby enabling any Residual Power associated with the load to equal the desired output power and therefore conserve battery input power and extend the life of the batteries.

It is another object of the present invention generate a feedback signal representing the desired operating condition of the load, compare the feedback signal with a variable time based electrical reference signal and generate the Pulse Time Modulated signals based on the comparison.

It has been found, in actual tests, (depending upon the type of energy storage device tested) that applying as little as 10% of the continuous maximum battery voltage to the load may be sufficient to maintain the desired operating condition such as temperature. This novel control circuit can be advantageously used with existing alternating current devices to minimize power use.

To accomplish this novel battery saving operation, a heat sensor, such as a tempistor or thermistor, and preferably an LM 34 thermistor made by National Semiconductor, provides the proper control.

In addition, it is an object of the present invention to provide a portable energy storage device comprising an external power source to bring the device load to a desired operating condition, internal batteries to power the device only in its portable state, and an electrical circuit coupled between the internal power source and the load for using pulse time modulated signals for regulating the power applied to the load in an amount sufficient only to maintain the stored energy of the device at the desired operating condition so as to conserve and extend internal battery life.

Thus, the present invention relates to apparatus for extending the life of batteries in a portable energy storage device comprising an external power source for causing the device load to reach a designated operating condition, P_(O); an internal power source in the device for supplying input power, P_(IN), to the load only when the external power source is disconnected from the device and making the device portable; and a pulse time modulated circuit coupled between the internal power source and the load for using pulse time modulated signals to cause input power, P_(IN), to be supplied to the load in an amount substantially equal to the device power losses, P_(L), sufficient only to maintain the designated operating condition, P_(O).

The present invention also relates to a method of extending battery life in a portable energy storage device and obtaining a desired output power, P_(O), from an electrical load, where P_(O)=P_(IN)−P_(L)+P_(R), comprising the steps of: supplying a continuous external power input, P_(IN), to the load to achieve the desired output power, P_(O), and create a residual, or stored power, P_(R); disconnecting the device from the external power source and automatically causing internal batteries to drive the load; and automatically reducing the input power, P_(IN), to an amount sufficient only to replace system and load losses, P_(L), using Pulse Time Modulation to thereby maintain the desired power output, P_(O), equal to the residual power, P_(R), with reduced input power, P_(IN).

The present invention also relates to apparatus for extending battery life in a portable energy storage device and automatically obtaining a desired output power, P_(O), from an electrical load of a system with reduced input power, P_(IN), where P_(O)=P_(IN)−P_(L)+P_(R) where P_(L)=Power losses expended in the load as well as any system losses, and P_(R)=residual Power or energy stored in the load at the desired output power, comprising an external power source for supplying continuous input power, P_(IN), to the load to achieve the desired output power, P_(O), (e.g. preheat) with an accompanying residual power, P_(R), internal batteries that are automatically coupled to drive the load only when the external power source is disconnected; and a pulse time modulation circuit is coupled between the internal batteries and the load for automatically supplying Pulse Time Modulated power to the load to reduce the input power, P_(IN), applied to the load to an amount sufficient only to replace the power losses, P_(L), thereby just maintaining the residual power, P_(R), equal to the desired output power, P_(O), to conserve electrical power and prolong the life of the internal batteries.

The present invention also relates to a method of extending the life of batteries in a portable energy consuming device comprising the steps of: coupling an external power source to the device to cause the device load to reach a designated operating condition, P_(O), without using the internal batteries (thereby extending the battery life); supplying power, P_(IN), to the load with the batteries only when the external power source is disconnected from the device to make the device portable; and coupling a circuit between the internal batteries and the load that uses pulse time modulated pulses to automatically cause the input power, P_(IN), to be supplied to the load in an amount substantially equal to the device power losses, P_(L), sufficient only to maintain the designated operating condition, P_(O), thereby extending the life of the internal batteries.

BRIEF DESCRIPTION OF THE DRAWINGS

These and other more detailed objects of the present invention will be disclosed more fully when taken in conjunction with the following DETAILED DESCRIPTION OF THE DRAWINGS in which like numerals represent like elements and in which:

FIG. 1 is generalized block diagram of the present invention;

FIG. 2 is a block diagram illustrating the use of an external power source only to bring an energy consuming device (device) to a desired operating level and then using an internal power source to just maintain the desired operating level and further illustrating the option of using the external power source to charge the internal power source (batteries) during the time that the device is connected to the external power source;

FIG. 3 is a block diagram illustrating the external power source connected to a device for bringing the device to a desired operating level while simultaneously charging the internal batteries of the device and, further, illustrating the mechanical connector that disconnects the internal power source (batteries, in this instance) from the load while the device is coupled to the external power source;

FIG. 4 is a block diagram illustrating the energy consuming device in its portable state with a control circuit operating an electronic power switch to provide pulse time modulated power to the load to only maintain the desired operating level of the device.

FIG. 4 is a block diagram illustrating a base unit on which a flat clothes iron is placed and illustrating the electrical connections from the external power source to connectors on the base unit for engaging corresponding connectors on the flat clothes iron to both bring the flat clothes iron to a desired temperature (operating level) while simultaneously charging the internal batteries associated with the flat clothes iron;

FIG. 5 is a schematic diagram illustrating an energy consuming device such as a hair curling iron mounted in a base unit and illustrating the external electrical connections for both preheating the device while simultaneously charging the device internal batteries; and

FIG. 6 illustrates a control circuit shown in commonly assigned co-pending provisional patent application Ser. No. 60/573,716 that can advantageously be used with the present invention.

DETAILED DESCRIPTION OF THE DRAWINGS

FIG. 1 is a generalized block diagram of an energy storage device 10 of the instant invention. An energy storage element 12 is shown as a resistive heating element 22 and a temperature sensor 89. In this generalized embodiment, a first power source 14, has AC power applied from a wall socket in the normal fashion and provides the AC on lines 16 and 16′ to an AC/DC converter 30. The DC output of the AC/DC converter 30 has a negative output to ground via contacts 17 of the converter (which, as will be discussed hereafter, may be a base unit in which the energy storage device 10 is placed when not in use) and a positive output of 8.4 volts in the present example via contacts 19. The positive output voltage via contacts 19 is coupled to contacts 23 of a double pole, double throw switch 21. When switch 21 arms are in the position shown, electrically engaging corresponding contacts 23, the energy storage device is in the preheat condition. The positive voltage is coupled on conductor 15 to the control circuit 70 (shown in detail in FIG. 6) that provides full power to the heating element 22 to preheat it to a predetermined temperature. At the same time, the positive voltage is coupled on conductor 27 to Lithium-Ion battery circuit 20 to charge up cells 29 and 31 to fill voltage. It will be understood that circuit 20 may contain well-known circuits to limit the charging voltage to a predetermined amount as well as to limit the amount of current received by the battery cells 29, 31. Thus, the battery power of the cells 29, 31 is conserved inasmuch as the external power source (from the AC/DC converter 30) is used to preheat the heating element 22.

When the device 10 is preheated to the proper temperature (which may also be regulated with devices such as thermocouples and the like), the switch arms 21 are moved to contacts 25 (either manually or by the removal of the portable energy storage device from a base) and power from the battery cells 29, 31 flows through conductor 27 to switch arms 28 and conductor 15 to the control circuit 70. The energy storage device is now portable and operates from its internal battery cells 20, 31. This energy storage device has a DC heating element (energy storage device) 22 that is preheated by DC power from the AC/DC rectifier circuit 30 and then operated as a portable device using DC power from its own internal batteries.

An alternate embodiment of the energy storage device is disclosed in FIG. 2 wherein is shown a block diagram 10 illustrating a second embodiment of the present invention. As can be seen, an energy storage device 12 (hereinafter called “device”) has an external power source 14 removably coupled to the device 12 by means of conductors 16 to an AC load element 18 located within the device to cause the device 12 to reach a desired operating level. Then, when the desired operating level is reached, the external power source 14 is disconnected from the device 12, device 12 becomes portable, and an internal power supply 20 is coupled to its own DC load element 22 to just maintain the desired operating level of the device 12.

Of course, the internal power source 20 may consist of the internal batteries and a pulsing circuit as will be shown hereafter to pulse the power of the internal batteries to the load. In such case, the life of the internal batteries is extended as will be disclosed hereafter.

Consider, as an example only, a hair curling iron. The iron has a metal mass serving as the heated surface and it must be raised to a sufficiently high temperature to enable it to be used. This is accomplished in the prior art by the use of alternating current (AC) and it takes several minutes to bring the metal mass to a temperature sufficient for use in curling hair. Then when it is used, the AC power cord must remain attached to keep the iron hot.

It is highly desirable to make the curling iron portable and eliminate the physical interference of the AC cord. However, if the curling iron is made portable, no cord is attached and no AC is used. Thus, the internal power source, without AC, must be placed under a severe power drain to bring the device to the desired operating level (in this example, temperature).

Thus, it can be seen with the block diagram of FIG. 2 that if the device 12 is a hair curling iron, it can be heated to the desired operating level or temperature with the external ac power source 14. When the mass of the curling iron reaches the desired operating level, or temperature, the AC cord 16 is disconnected from the hair curling iron 12 in a well know manner as by means, for example, of unplugging AC connectors from the device 12. An internal power source, as will be shown hereafter, is then automatically utilized to just maintain the desired operating level or temperature.

In the generalized embodiment shown in FIG. 2, the external AC power source utilizes and is connected to its own AC heating element located within the device 12. Once the AC cord is disconnected from the device 12, the internal DC power source 20 is automatically connected to its own DC heating element 22, as will be explained hereafter, to cause the device 12 to maintain its desired temperature.

Also, as shown in FIG. 2, the external power source 14 may be used to charge the internal power source 20 with the output of an AC/DC converter by means of a second conductor 24 whenever the device 12 is mounted in a base unit as will be shown hereafter.

Of course, the device 12 illustrated generally in FIG. 2 could represent any hair management device, in addition to a hair curling iron, such as a blow dryer, that requires large amounts of energy to get the device to the proper temperature. Device 12 in FIG. 2 could also represent a flat clothes iron, a soldering gun, a glue gun, a rotating mass, and the like. As used herein, the term “energy storage device” is intended to include any of the energy storage devices mentioned in this paragraph.

FIG. 3 is a schematic representation of a device 12 and illustrating a generalized version of the electronics associated therewith. The device 12 sits in a base unit (not shown for simplicity of the drawings) that has a connector or jack 26 that functions as set forth hereafter. The internal power source 20 in FIG. 3 is coupled, through switch 28, to a DC heating element 22. When the device 12 is to be brought to a desired operating level, such as temperature, an external AC source 14 and connected power cord 16 having on the end thereof an elongated connector 26 of any well-known type in the art (connected to a base unit if desired as shown in FIG. 5) can be inserted in a mating receptacle in the energy storage device 12 in a well-known manner to connect the external power source to an internally located AC load such as heating element 18, for example only, on lines 32 and 34.

At the same time, if desired, the AC input can be connected to an AC/DC converter 30, either internal or external (shown here as internal) that can be used to charge the internal batteries 20 in a conventional manner as explained earlier.

When the AC heating element 18 causes the device 12, here a temperature device, to reach the desired operating level (store the desired temperature in this case), the energy storage device is withdrawn from the mating receptacle connector 26, on a base unit if desired, to make the device portable. When that happens, switch 28 returns to its normally closed position thereby connecting internal power source 20 to its own DC load 22 on line 36. As will be shown hereafter in relation to FIG. 4 and FIG. 6, a control circuit 38 provides just sufficient energy from the internal power source 20 to cause the device 12 to only maintain the desired operating level.

The circuit shown schematically in FIG. 4 includes control circuit 38 that is powered by the internal power source 20. When the connector or elongated prong 26 (here represented by a phantom line) is disconnected from device 12, switch 28 closes as explained earlier.

An electronic switch 40, such as a power FET, is opened and closed by the control circuit 38 with the use of Pulse Time Modulated signals to modulate the power signal to load 22 from the internal power source 20 to provide only sufficient power to maintain the desired temperature. A light emitting diode (LED) 42 may be utilized, if desired, to let the user know that the control circuit 38 is functioning.

The novel invention works well with any load requiring heavy current to bring it to a desired operating level as explained earlier. FIG. 5 illustrates a flat clothes iron 46 mounted on a base unit 44 shown in cross-section. The flat iron 46 has a handle 47 that is sufficiently temperature insulated from the heated body portion of flat iron 46 to enable a user to pick up and use the heated flat iron 46.

The novel invention works well with any load requiring heavy current to bring it to a desired operating level as explained earlier. FIG. 5 illustrates a flat clothes iron 46 mounted on a base unit 44 shown in cross-section. The flat iron 46 has a handle 47 that is sufficiently temperature insulated from the heated body portion of flat iron 46 to enable a user to pick up and use the heated flat iron 46.

It will be noted in FIG. 5 that an external power source 14 is coupled through cord 16 to a connector that is plugged into the base unit in a well-known manner as explained previously. In this example, external ac power is connected directly to connector 52 by conductor 50 to preheat the iron when a switch on the base (not shown here) is operated by a user when the user desires to use the flat iron. At the same time, if desired, the internal power source can be charged by the output from an AC/DC converter 48 on connector 26. When the iron reaches the desired temperature as may be shown in any well-known manner, the iron may be removed from base unit 44 and thus becomes a portable iron. It should be noted that while the AC/DC converter 48 is shown to be a part of the base unit 44, it can be external to the base unit 44 if desired. Thus, the flat iron 46 shown in FIG. 5 utilizes first and second heating elements located internally of the flat iron 46. One heating element is an AC heating element (to be used by the external power source) and the other is a DC heating element (to be used by the internal power source).

The flat iron 46 could, if desired, have only one heating element and that is a DC heating element that would be used first during the preheating on the base unit 44 and then, when the flat iron 46 is disconnected from the base unit 44 to make the flat iron portable, the single DC heating element would be connected to the internal power source 20 to just maintain the desired temperature.

As shown in FIG. 6, the base unit 44 has an AC/DC converter 48 associated therewith, either internal (as shown) or external to the base unit 44. The device, then, uses the DC power source for preheating a single DC heating element and when the device is disconnected from the base unit 44 to make the device portable, the internal DC source is coupled to the same single DC heating element. Such a connection would be obvious to one skilled in the art given the assignment of creating such connection and therefore is neither shown nor explained here.

FIG. 7 illustrates a base unit 44 on which a hair curling iron 64 (shown in phantom lines) could be mounted for preheating and charging of its internal power supply. The internal power supply may be batteries as is well known in the art. Again, an AC power source, represented by electrical plug 14, is connected by cord 16 to a connector 56 on the base unit 44 as explained earlier. Also as explained earlier, the hair curling iron 64 could have a single heating element for both preheating and portable operation. As shown, however, a first heating element is used for preheating with the external AC power source and a second heating element is used for portable operation with the internal power source.

The AC input from the external power source is connected directly to connector 62 on the base unit 44 while the DC power for simultaneously charging the internal power source comes from an AC/DC converter 58 whose DC output is coupled to connector 60. The power cord 16 terminates at the base unit 44 with a connector 56. Advantageously, connector 56 is identical to the connector 62 on base unit 44. If, for any reason, the portable operation of the device 64 is prohibited, the AC connector 56 can be plugged directly into the device 64 where power is normally supplied by connector 62. In such case, the hair curling iron 64 may advantageously continue to be used as a conventional cord attached, non-portable hair curling device.

In any use of batteries with a heating device, the batteries must not be subject to heating from the heating elements. In a hair curling iron, the batteries may be placed in a heat insulated handle as is well-known in the art and which is heat insulated from the heating element.

FIG. 8 is a schematic diagram of the electronic control circuit for the novel invention herein that supplies only sufficient Pulse Time Modulated energy to the device to replace only load losses and to maintain the desired power output and thereby conserve battery energy that would otherwise be wasted. This diagram has been explained in detail in co-pending commonly assigned provisional patent application Ser. No. 60/573,716 incorporated herein by reference in its entirety.

Briefly, however, unit 78 is a detector that senses the desired operating level (e.g. a temperature sensor 80 as shown in FIG. 8). Oscillator 94 generates, in this case, a sawtooth wave output on line 96 that is coupled, along with the amplified detector 78 signal on line 90 to a comparator 92. As long as the amplitude of the amplified output of detector 78 on line 90 is greater than the amplitude of the oscillator 94 output on line 96, there is a constant output from the comparator 92 through resistor 100. This signal is coupled through switch 28 to the gate of power FET 102 causing it to conduct and apply maximum power to the load 22.

However, as explained earlier, to save the internal batteries, the device has, in this instance, an AC heating element 18 that is heated to bring the device to the desired operating temperature. As can be seen in FIG. 8, the device is first heated to the desired operating temperature with an external AC power supply 44. The external power supply 44 is coupled to the energy consuming device by means of, in this case, a male connector 26 that makes contact with points 75 and 76 (on line 16) to provide power to the AC load 18 in the device. Switch 74 is a double pole, single throw switch that first couples the external AC source to the AC load heating element 18. In addition, the other half of switch 74 couples the internal power supply (batteries) to the control circuit described above. Because the control circuit uses such little power, little drain is placed on the internal batteries during the time the external power supply is bringing the device to the desired operating temperature.

As explained earlier, the male connector, represented by phantom line 26, physically opens switch 28 thus preventing the FET from receiving any signal from the control circuit of the device when the device is on the base unit. Thus no power is being supplied to the DC load 22 during the time that the external AC power source is heating the device to the desired operating temperature with the use of AC heating element 18. When the AC heating element or load 18 causes the device to reach the desired temperature (which can be indicated in a well known manner by illumination of an LED), the device is removed from its base unit and the male connector 26 is removed from the portable energy storage device closing switch 28 and allowing the signal from the comparator 92 of the control circuit to be connected to the power FET 102 which begins to apply power to the DC load 22. Because DC load 22 is in physical proximity to the metal mass that has been heated by the external power source 44, the DC load 22 is already heated to the approximate desired operating temperature and the power FET 102 now is Pulse Time Modulated by the control circuit to provide just enough energy to DC load 22 to maintain the desired operating temperature of the device.

An LED 103, if desired, may be coupled across FET 102 and pulses with the pulsing of the FET to indicate to the user that the control circuit is functioning.

Thus, there has been disclosed a novel improved portable energy storage device that uses an external power source to cause the device to reach a desired operating level and then when the device is removed from its base, the external power source is disconnected from the device and the internal power supply is then automatically connected to a DC load to maintain the desired operating level of the device. A control circuit is coupled between the internal power source and the DC load to Pulse Time Modulate the signal applied thereto to replace only load losses and to just maintain the desired operating level. As explained earlier, the desired operating level is intended to mean a desired operating temperature, a desired operating rpm, or any other type of load operating condition that has stored kinetic or potential energy that will maintain the desired operating condition if sufficient energy is provided to just replace the device losses.

While particular embodiments of the invention have been shown and described in detail, it will be obvious to those skilled in the art that changes and modifications of the present invention, in its various embodiments, may be made without departing from the spirit and scope of the invention. Other elements, steps, methods, and techniques that are insubstantially different from those described herein are also within the scope of the invention. Thus, the scope of the invention should not be limited by the particular embodiments described herein but should be defined by the appended claims and equivalents thereof. 

1. Apparatus for extending the life of at least one battery in a portable energy storage device having an energy storing and energy consuming load and including device power losses, P_(L), comprising: an external power source coupled to the portable energy storage device to cause the energy load to store a desired residual amount of power, P_(R); at least one internal energy cell for supplying electrical power, P_(IN), to the energy consuming load only when the external power source is disconnected and the device is portable thereby extending the life of the at least one internal energy cell; and a power regulating circuit coupled between the energy consuming load and the at least one internal energy cell for generating pulse time modulated signals that control the battery power to the energy consuming load such that the input power, P_(IN), substantially equals power losses, P_(L), thereby enabling the stored residual power, P_(R), to provide the output power, P_(O), and extend the life of the batteries.
 2. The apparatus of claim 1 further comprising: a base unit for receiving the portable device; and the external power source being coupled to the base unit to provide power to the portable device to enable it to store the desired kinetic/residual amount of power.
 3. The apparatus of claim 2 wherein the portable device is a hair curling iron and the external power source preheats the hair curling iron to a desired temperature.
 4. The apparatus of claim 1 wherein the power regulating circuit further comprises: a control circuit coupled between the at least one internal energy cell and the energy storage load for generating pulse time modulated signals that automatically reduce the at least one energy cell input power, P_(IN), applied to the load to an amount sufficient only to replace the power losses, P_(L), thereby just maintaining the residual power, P_(R), to equal the desired output power, P_(O), to conserve electrical power and prolong the life of the load.
 5. The apparatus of claim 2 wherein the external power source simultaneously charges/recharges the at least one energy cell whenever the device is in the base unit and the external power source is providing power to the portable device to enable it to store the desired residual amount of power.
 6. The apparatus of claim 5 further including: the internal power cell being in the form of at least one battery; and an AC/DC converter associated with the base unit for converting the AC wall socket power to DC power that is provided to the portable device to enable it to store the desired residual amount of power while simultaneously charging/recharging the at least one internal battery.
 7. A method of extending the life of at least one battery in a portable energy storage device having an energy consuming and storing load and power losses, P_(L), comprising the steps of: supplying input power, P_(IN), to the device load from an external power source to achieve the desired output power, P_(O), with an accompanying residual power, P_(R) and to simultaneously charge/recharge the at least one battery as necessary; automatically connecting the at least one battery to the load only when the external power source is disconnected; and using variable rate pulse time modulated signals to automatically reduce the input power, P_(IN), supplied by the at least one battery to an amount sufficient only to replace the power losses, P_(L), thereby just maintaining the residual power, P_(R), equal to the desired power output, P_(O), to conserve input power and prolong the life of the load and extend the life of the at least one battery.
 8. The method of claim 7 further comprising the steps of: placing the portable energy storage device in a base unit; and coupling the external power source to the base unit to cause the portable device to store the desired residual amount of power supplied by the external power source.
 9. The method of claim 8 further comprising the steps of: forming the portable device as a hair curling iron having the energy consuming and storing load; and preheating the hair curling iron load to a desired temperature with the external power source.
 10. The method of claim 7 further comprising the step of: coupling a control circuit between the at least one internal battery and the energy storage load for generating pulse time modulated signals that automatically reduce the at least one battery input power, P_(IN), applied to the energy storage load to an amount sufficient only to replace the power losses, P_(L), thereby just maintaining the residual power, P_(R), to equal the desired output power, P_(O), to conserve electrical power and prolong the life of the at least one battery and the load.
 11. The method of claim 8 further comprising the step of: simultaneously charging/recharging the at least one battery whenever the device is in the base unit and the external power source is providing power to the portable device to enable it to store the desired residual amount of power. 